ORIGINAL: Taurus Flyer

Ed,

When we see the side view of a Kaos we see the tank already has a low position related to the spray bar and that can give some troubles. (red arrows picture 2) Too rich fuel /air mixture ratio inverted.

When I look at the pictures of your Kaos (picture 3), it looks like you also did make the nose longer and did mount the engine in a more forward position, see the grey sketch and orange questionmark in picture 2. Maybe because of the back plate mounted mixture needle valve?

Can you make a sketch showing us the distances and dimensions? Especially the distance between the front side of the tank and the back plate of the engine. (blue arrows)

When you do not use a fuel pressure regulator or pump it is important to keep that distance as short as possible.

If not, I think the engine can get too much fuel in nose down going directions as result of the hydrostatic pressure. (of course until the moment during flight the clunk will be above the fuel level and the line is empty in short time!!) Remember you adjust the engine in nose up position so the mixture ratio already will be rich in horizontal ATTITUDE.

Also for this problem a regulator is a solution, first the mixture will always be optimal, not too rich, second the chamber of the regulator does contains an extra amount of fuel.
My Taurus has the spray bar also above the centre line of the fueltank because this engine is much larger than the engine the plane was designed for, see picture 4.

Maybe you can use this information.
If your dimensions are as on the plans, I would check them with the original dimensions.

Cees